1. Field of the Invention
The present invention relates to planar optical displays, and, more particularly, to an ultrathin display panel and a method of making an ultrathin display panel.
2. Description of the Background
Optical screens typically use cathode ray tubes (CRTs) for projecting images onto the screen. The standard screen has a width to height ratio of 4:3 with 525 vertical lines of resolution. An electron beam is scanned both horizontally and vertically across the screen to form a number of pixels which collectively form the image.
Conventional cathode ray tubes have a practical limit in size, and are relatively deep to accommodate the required electron gun. Larger screens are available which typically include various forms of image projection. However, such screens have various viewing shortcomings including limited viewing angle, resolution, brightness, and contrast, and such screens are typically relatively cumbersome in weight and shape. Furthermore, it is desirable for screens of any size to appear black in order to improve viewing contrast. However, it is impossible for direct view CRTs to actually be black because they utilize phosphors to form images, and those phosphors are non-black.
Optical panels may be made by stacking waveguides defining a wedge and having a narrow inlet face along the bottom of the wedge and a vertical outlet screen disposed obliquely to the inlet face. Such a panel may be thin in its depth compared to its height and width, and the cladding of the waveguides may be made black to increase the black surface area, but such a panel may require expensive and cumbersome projection equipment to distribute the image light across the narrow inlet face, which equipment thereby increases the total size of the panel.
Therefore, the need exists for an optical panel which possesses the advantages corresponding to a stacked waveguides panel, but which does not require the use of expensive and cumbersome projection equipment, nor suffer from the increase in size necessitated by such equipment.